JPS602083B2 - Rotating filter and its refinishing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to filter devices, particularly rotary filter devices of the type commonly used in the pulp and paper industry.

Rotary filter devices have been used for many years in a variety of applications, particularly in the pulp and paper industry.

The device was cylindrical in shape and constructed of a metallic material, typically stainless steel or other metal coated with stainless steel. The outer surface consists of a filter material, typically a metal or synthetic resin mesh.
By applying a vacuum or other suction force from within the filter, permeate material, such as water-saturated pulp, chemicals, or various fluids, is deposited on the filter material and fluid is extracted from the pulp. The pulp is then removed as the filter finishes its rotation cycle, typically by the use of a raking device or air pressure appropriately placed against the filter surface; The settings are set to match the filter diameter, pulp concentration, and other variables so that the desired degree of filtration is achieved by the end of the process.
The filter is positioned so that its lower part is submerged in a container of saturated pulp. Therefore, the monkey process is
The filtered pulp is removed from the filter just before the filter surface is reversed in the container, and when the filter surface is rotated forward in the container, the saturated pulp adheres to the outer surface due to suction and the cycle repeats. It becomes one continuous process. The follower device generally consisted of an inner cylindrical surface having a plurality of support structures extending radially outwardly from the cylindrical surface and extending longitudinally the entire length of the inner surface.

The support structure is provided with a groove or indentation adapted to receive a continuous helically wound wire thereabout. These windings form a partial surface for supporting the filter material. In prior art devices, the support structure and windings were made of metallic material, typically stainless steel. The device is then covered with a flexible mesh filter material that forms the outer surface of the filter. Although there are a number of problems associated with the use of such conventional devices, these devices have been used without substantial modification or improvement for more than two years.

During use, some exposed surfaces of the filter are continuously brought into contact with various corrosive substances, such as chlorides, which corrode all exposed metal surfaces. These filter devices are typically very large, eg, 10 feet (about 3 meters) in diameter, and require significant capital, typically between $200,000 and $300,000. However, if used in a corrosive environment, repairs or modifications may now be necessary, which may require the paper machine and other processes to be shut down for a significant period of time. Every time a paper machine is down, it means thousands of dollars in losses, and the longer a paper machine is down, the greater the loss. Under typical usage conditions, the filter must be reassigned within two to three years due to corrosion.

The grooves in the winding support structure become completely eroded and are no longer of practical use as stable supports for the windings. The windings then move or slide freely, making it impossible to maintain uniformity in the sanding process. Rough surfaces often cause the windings to break, causing tearing and rupture of the filter material, and each time such an incident occurs, it is necessary to shut down the process until necessary repairs are made. It will be necessary to remove the filter material and windings and sand and re-groove the winding support structure.
Stainless steel windings are a safety hazard because they must be helically wound under tension on a drum, and if they break, people in the vicinity may be injured. be. The present invention provides an improved rotary filter in which the filter support structure is covered with a synthetic resin material that has superior corrosion resistance compared to metal structures used heretofore.

A synthetic resin cover can be installed during manufacture, which can extend the initial life of the filter before replacing the cover. By placing a synthetic resin cover over the support structure, the filter can be refinished in a very short time, eliminating the need for polishing or regrooving. The synthetic resin cover can be prefabricated to the desired dimensions, in particular containing grooves of the desired spacing and depth. The use of a synthetic resin cover allows the use of synthetic resin windings, which was hitherto not practicable due to the continuous abrasion resistance of the synthetic resin material against the metal surface of the grooved support structure. do. In rotating filters where the support structures are placed sufficiently close together,
Since the synthetic resin cover has a rounded outer surface to receive the filter material, it is possible to eliminate the need for winding while sufficiently maintaining the cylindrical shape of the cylindrical surface. The present invention will be explained below based on an embodiment shown in the drawings. As shown in Figure 1, the rotating filter is
It consists of a large drum-like device having an internal cylindrical surface 2 connected at each end to an end support structure 1.

The bottom surfaces of a plurality of support structures 3 are connected to the inner cylindrical surface 2 . These support structures extend longitudinally over the length of the filter and are equally spaced at appropriate distances. The winding 4 is embedded in a number of notches on the synthetic resin cover 5 and wound helically around the drum. Filter material 6 is wound onto the cylindrical surface formed by winding 4 . This filter material 6 is held in place by a plurality of metal bands 7. In use, the rotary filter is continuously rotated in a predetermined direction so that its bottom protrudes into a container of saturated pulp.

The suction applied inside the rotary filter causes the saturated pulp to adhere from the container to the filter material 6 as the rotary filter rotates. The mesh size of the filter material 6 allows only the fluid to be drawn into the drum, while the pulp material remains attached to the outer surface.
becomes. The fluid extracted from the pulp is pumped from the drum through pipe 01 and sent elsewhere in the mill where it is normally to be recycled. The sieved valve is removed from the filter surface near the area where it is returned into the container. FIG. 2 shows a portion of the inner cylindrical surface 2 fitted with a support structure 3, the metal top surface of which has a number of grooves formed therein.

The synthetic resin cover 5 is fitted onto the support structure 3 with an internal region 9 that is made to fit closely against the support structure 3 of predetermined dimensions. After the synthetic resin cover 5 is once attached onto the support structure 3, holes are drilled in both sides of the cover 5 and the support structure 3, and holes are inserted into these holes in order to fix the cover 5 in place. You may need to iron the metal pin. The top surface of the cover 5 is provided with a series of notches 8 for receiving windings of predetermined thickness. The winding, filter material, and metal band hold the synthetic resin cover in the stereotactic layer when assembly is complete. FIG. 3 is a partial cross-sectional view of the end of the rotating filter shown in FIG.
The support structure 3 is in contact with the end support structure 1. The support structure 3 has a plurality of notches 8, and the winding 4 is fixed to the end support structure 1 and extends from there through each notch 8 to be wound helically around the cylinder. . Then, the filter material 6 is placed over the surface formed by the winding wire, whose both ends are fitted into the concave portion 13 formed along the outer circumferential surface of the end support structure 1 . A metal band 7 is wrapped around the outer circumferential surface of the end support structure 1 and further wrapped at several locations on the circumferential surface of the cylinder to hold the filter material 6 in position. A rotating filter according to the invention as shown in FIG. 1 has several advantages over conventional structures.

The synthetic resin cover 5 has superior corrosion resistance compared to the metal surface of conventional filter support structures, and can lengthen the period of time that requires replacement, as well as extend the service life of the filter. can be done. The use of the synthetic resin cover 5 also allows the use of synthetic resin windings 4, which may have a longer corrosion life than the previously used stainless steel wires. The metal-on-metal interface between the support structure and the windings can trap special corrosive contaminants and cause corrosion due to abrasion. Bonding the plastic surfaces together reduces the amount of wear between these surfaces, and special corrosive contaminants will not adhere to the plastic as they would to metal.
A synthetic resin surface may also improve the performance of the filter because it provides less resistance to fluid flow. Furthermore, when wire windings are used, the grooves in the plastic cover can be spaced much further apart than the grooves in the metal support structure, increasing the effective cross-section area. As a result, the overflow processing speed is increased. When it becomes necessary to replace the synthetic resin cover, that is, in the first case, when it becomes necessary to refinish the existing rotary filter, the band 7 is first removed so that the filter member 6 can be removed. .

The winding 4 is then removed to expose the support structure. If the rotary filter is not equipped with a synthetic resin cover 5, it is sufficient to simply place a synthetic resin cover on the existing metal support structure 3, or if the rotary filter is already equipped with a synthetic resin cover. If so, the cover can be removed and replaced with a new one on the support structure. If the plastic cover is entirely in the stereotactic layer and windings have to be used, the windings are wound helically around the cylinder via the notches. Filter material 6 is then placed around the drum and held in place by band 7. This process can be completed in one-tenth or less of the time traditionally required to reassign a filter by polishing the metal support structure and cutting new grooves into it. . As shown in FIGS. 4 and 5, the invention also allows the use of windings to be completely avoided.

In this case, the synthetic resin cover 11 is ironed directly onto the support structure 3 in a similar manner. Synthetic resin cover 11
The upper surface 12 of the filter is somewhat rounded to match the outer circumferential surface formed by positioning the filter material around a cylinder on the support structure. The filter material 6 is attached to the support structure 3, that is, the synthetic resin cover 1.
1 and held in place by band 7. Heretofore, it has not been possible to place filter materials directly on support structures, whether of synthetic resin or metal construction. As used herein, the term synthetic resin is intended as an umbrella term to include all synthetic monofilaments such as polyethylene, polypropylene, Kynar®, and the like.

Polyethylene, especially ultra-high molecular weight polyethylene, has high abrasion resistance and is economical, but it does not have great chemical resistance and should basically be used in a neutral environment. Where percolate paper permits the use of that liquid, polyethylene is the most desirable synthetic resin available. If there are not many exposed areas to wear, Kynar® is a suitable material since it is practically chemically inert and particularly resistant to acidic solutions. Since the rotating filter according to the present invention has few exposed parts that are subject to wear,
In particular, Kynar (trade name) is suitable. Polyethylene has good abrasion resistance and chemical corrosion resistance, but its sensitivity to heat limits its use. The above and all similar substances may be used as materials of construction for the filter material, the windings (if used) and the cover for the support structure, depending in each case on the characteristics of the particular environment of use. It can be used as a selection.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of the rotating filter;
FIG. 2 is a perspective view showing how a synthetic resin cover with appropriate grooves is attached to a worn support structure; FIG. 3 is a partial sectional view of one end of the rotary filter shown in FIG. 1; Fig. 4 is a perspective view showing a state in which a grooveless synthetic resin cover is attached to the support structure, and Fig. 5 is a perspective view of the rotary filter shown in Fig. 1 with the synthetic resin cover of Fig. 4 attached. FIG. 3 is a partial cross-sectional view of one end. DESCRIPTION OF SYMBOLS 1... End support structure, 2... Internal cylindrical surface, 3... Support structure, 4... Winding wire, 5, 11... ...Synthetic resin cover, 6...
...Filter material, 7...Metal band, 8.
...Notch, 9...Inner area, 10...
...Pipe, 12...Top surface of synthetic resin cover,
13... Concavity. FIG. 4 FIG. 5 FIG. l FIG. 2 FIG. 3

Claims (1)

[Scope of Claims] 1. An internal cylindrical surface, a plurality of support structures arranged at appropriate intervals and extending in the longitudinal direction of the cylindrical surface, and a synthetic resin cover fitted onto the support structures; A rotary filter comprising a combination of a filter material that extends over an outer circumferential surface formed by the support structure and is covered with the support structure, and a device for firmly holding the filter material on the support structure. . 2. The rotary filter according to claim 1, wherein the filter material is made of a synthetic resin material. 3 Claims in which the synthetic resin cover has grooves arranged at appropriate sizes and intervals on its outer surface, and includes a wire fitted into the grooves and wound helically around the filter. 1. The rotary filter according to 1. 4. The rotary filter according to claim 3, wherein the wire is made of a synthetic resin material. 5. A plurality of metal support structures appropriately arranged on the inner cylindrical surface, a wire rod fitted into a groove formed in the support structure and wound helically around the filter, and a metal support structure formed by the wire rod. for refinishing a rotary filter of the type consisting of filter material spread on the outer circumferential surface of the rotary filter.
removing the filter material to expose the wire wrapped around the filter; and removing the wire wrapped around the filter to expose the support structure.
a step of covering each support structure with a synthetic resin cover of a predetermined size; a step of placing a new filter material around the rotating filter and resting it on the synthetic resin cover; and a step of placing the filter material on the support structure. A method consisting of the step of fixing to the body.